Deep Thought wrote:BigRed wrote:So de-tuning that structure will still be necessary.
Happily, that is very easy to do. Interrupt the ground wire and wrap about 40 turns of #8 wire around the pole to form a coil. DC continuity is maintained but RF won't bother to try to get through. You can also resonate it with a capacitor if necessary.
That coil in the ground wire near the base of the pole is a neat idea but I think that you've overlooked a couple of things . . .
1st, if the pole is supporting a communications (STL) antenna you'll have to also add an isolation coil for that feedline as well. A sample loop isolation coil should work just fine for that.
2nd, while that approach will be fine and dandy for DC and power line frequencies it will have the same effect for a lightning strike discharge as it does for the AM band. (The impulse frequency of a lightning strike is somewhere in the middle of the AM band, or so I'm told . . . ) So either a ball gap should be included across the coil or, perhaps, forgo the coil in the ground wire and use a single de-tuning skirt wire with coil/capacitor so that the ability of that ground wire to pass a lightning discharge to ground is not compromised.